The synthesis and molecular and crystal structures of 1-methyl-2-carboxy-1,2-dicarba-closo-dodecaborane(12), 1-phenyl-2-carboxy-1,2-dicarba-closo-dodecaborane(12) and 1-phenyl-2-benzoyl-1,2-dicarba-closo-dodecaborane(12)

Venkatasubramanian, U.; Donohoe, D.J.; Ellis, D.; Giles, B.T.; Macgregor, S.A.; Robertson, S.; Rosair, G.M.; Welch, A.J.; Batsanov, A.S.; Boyd, L.A.; Copley, R.C.B.; Fox, M.A.; Howard, J.A.K.; Wade, K.

Abstract

The structures of 1-Me-2-COOH-1,2-closo-C2B10H10 (1), 1-Ph-2-COOH-1,2-closo-C2B10H10 (2) and 1-Ph-2-COPh-1,2-closo-C2B10H10 (3) have been determined by X-ray crystallography. In 1 the orientation of the COOH group is defined by theta(COOH) = 65.0(2)(syn)degrees, and this group H-bonds to that in a second molecule via a centrosymmetric eight-membered ring, R-2(2)(8). DFT calculations on the parent species 1-COOH-1,2-closo-C2B10H11 reveal that the structure with theta(COOH) = 90(syn)degrees is preferred, with a barrier to COOH rotation of approximate to 17 kJ mol(-1). Similar calculations on 1 yield a lower rotational barrier, approximate to 7 kJ mol(-1), because internal H-bonding is now denied. In compound 2 the COOH group is twisted to lower theta values [5.0(3)degrees and 39.7(3)degrees] but both crystallographically independent molecules exist as dimers in the solid state by virtue of R-2(2) (8) rings. Compound 2 crystallises from wet solvent as a monohydrate, the structure of which reveals a non-planar centrosymmetric R-4(4)(12) ring and near-orthogonal Ph and COOH substituents [theta(Ph) = 6.7(2) and theta(COOH) = 78.0(2)(syn)degrees]. In compound 3 molecular association by H-bonding is blocked, so 3 serves as a useful comparative structure for 2. (C) 2003 Elsevier Ltd. All rights reserved.

Citation

Venkatasubramanian, U., Donohoe, D., Ellis, D., Giles, B., Macgregor, S., Robertson, S., …Wade, K. (2004). The synthesis and molecular and crystal structures of 1-methyl-2-carboxy-1,2-dicarba-closo-dodecaborane(12), 1-phenyl-2-carboxy-1,2-dicarba-closo-dodecaborane(12) and 1-phenyl-2-benzoyl-1,2-dicarba-closo-dodecaborane(12). Polyhedron, 23(4), 629-636

• Journal Article Type: Article
• Publication Date: 2004-02
• Journal: Polyhedron
• Print ISSN: 0277-5387
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 23
• Issue: 4
• Pages: 629-636